The present invention relates to a process for obtaining an aroma concentrate that is enriched in lactones.
Aliphatic lactones, particularly internal esters of 4-, 5- or 6-hydroxyalkanoic acids having 6-20 carbon atoms comprise compounds of which it is known that they are responsible for part of the specific odour and taste of butter. They occur in butter in a concentration of 0.1-35 ppm (J.A.O.C.S. 42 (1965) 857-861 and J. Dairy Res. 43 (1976) 469-474).
For use in all kinds of foodstuffs the above-mentioned lactones are highly valued aroma compounds. That is why, already for some considerable time, lactones are also being prepared via chemical synthesis, with racemic mixtures being obtained.
Although attention has already been paid for a considerable time to the preparation of aroma compounds in a natural manner, and despite the fact that various analytical methods of identifying and isolating lactones have been developed on laboratory scale, up to now there is still no technically and commercially acceptable method known for the large-scale concentration of lactones from natural products.
In J.A.O.C.S. 47 (1970), 299-302 an analytical method for isolating lactones from materials like milk fats of cow and goat and from the crude fats of coconut, palm kernel, palm fruit and babassu nut has been described. The experimental procedure described in the article starts with a steam distillation for 4-5 hr at 180.degree. C. and a pressure of 2 mm Hg, the distillate being collected in a trap at -80.degree. C. The trap contents are extracted with ether and the residue of the extraction is saponified with a KOH-solution followed by an ether-extraction, after which the acids in the soap are liberated with sulfuric acid and recovered by yet another ether-extraction. After evaporation of the ether the hydroxy acids present are lactonized by dissolving the acid mixture in benzene and refluxing, while distilling of the water liberated from the hydroxy acids. The residual mixture is dissolved in light petroleum and extracted twice with triethanolamine. The triethanolamine soaps were washed with light petroleum and after evaporation of the solvent the residual lactone concentrate was distilled in a cold finger apparatus.